1. Field of the Invention
The present invention relates to an articulated arm for an awning, comprising a first arm part and at least a second arm part, wherein the first arm part and the second arm part are connected with each other via an articulation, the articulation axis of which runs transversely to the longitudinal axis of the arm parts, and wherein, in the first arm part, at least two springs adjacent to each other are arranged, with one end of the springs being fixed on the first arm part, and on the other end of the springs at least one flexible traction element is fixed which is led via the articulation into the second arm part, where it is fixed on the second arm part.
2. Description of the Related Art
One type of articulated arm is generally known from European patent number EP 0 489 186 A1. The articulated arm mentioned is used in a certain type of awnings, in so-called articulated arm or folding-arm awnings. Such awnings have an awning fabric, which is held upon a fabric winding spindle in such a way that it can be wound up and wound off. A forward end of the awning fabric is fixed on an extension bar, which is moved away from the fabric winding spindle, if the awning fabric is wound off the fabric winding spindle, and which is moved towards the same when the awning fabric is wound up. The extension bar on which the forward end of the awning fabric is fixed is, at the same time, over the at least one, usually two articulated arms, connected to a supporting part of the awning, e.g. a support tube.
Such an articulated arm typically has at least two arm parts which are connected with each other via an articulation, the axis of which runs transversely to the longitudinal axis of the arm parts. One arm part, which is generally designated as the upper arm is, at the same time, connected in an articulated way with its end facing away from the articulation to the supporting part of the awning, i.e. the support tube. The other arm part, which is generally designated as the forearm is, with its end facing away from the articulation, connected to the extension bar in an articulated way.
When the awning is completely reeled in, wherein the awning fabric is completely wound up on the fabric winding spindle, the articulated arm is bent to its maximum, i.e. the first and the second arm part are nearly parallel and adjacent to each other and run approximately parallel with the extension bar and the support tube. When the awning is reeled out to its maximum extent, i.e. if the awning fabric is completely wound off the fabric winding spindle, the articulated arm is stretched.
The articulated arm or the articulated arms of the awning have the function to push away the extension bar, when the awning fabric is wound off the fabric winding spindle, in order to pull away the fabric under tension when it is wound off the fabric winding spindle. For that purpose, in one of the arm parts, e.g. in the upper arm of the articulated arm, at least one spring is arranged, the one end of which is fixed to the first arm part, and to the other end of which an end of at least one flexible traction element is fixed, e.g. in the shape of a wire cable or a chain, which is led over the articulation that connects the two arm parts into the second arm part, where it is fixed with its other end onto the second arm part.
When the awning is reeled in and the articulated arm is bent to its maximum, the spring, which is usually designed as a tension spring, is stretched to its maximum. When the articulated arm is bent, the distance length between the fixation point of the traction element on the forearm and the fixation point of the spring on the upper arm is, namely, enlarged by the curve length of the bent articulation. The spring is, thus, when the articulated arm is bent, stretched to its maximum, so that the bent articulated arm is pre-stretched in its stretched position, with the effect that the articulated arm, when the fabric is wound off, stretches on his own.
In order to pre-stretch the articulated arm even in an awning with a relatively high extension length correspondingly in its stretched position, high spring forces are often required. The springs used have, thus, a very high spring constant. In awnings with high extension length, moreover, at least two springs or even more springs are used, which are adjacently arranged in the one arm part.
In these articulated arms, the at least two springs are typically connected with each other, on their free end, by means of a brace, wherein one single suspension is arranged on the brace, e.g. in the shape of a hook, on which, then, one single traction element is commonly fastened. The traction element, thus, has to take up the force of two or more springs. The traction element is, correspondingly, much more stressed as if it was connected to only one spring. This may result in reduction of the endurance of the traction element, i.e. the durability under load of the traction element is reduced when the awning is reeled in and reeled out. The traction element is exposed to repeated alternating stress, in particular in the region of the articulation, where it experiences a deflection, so that the one traction element can tear earlier.
It has therefore been suggested to use, instead of one traction element, a string of several traction elements, which are tied together on their one end, which is connected to the end of the springs. In this way, however, again only one fixing point of all traction elements with all springs is created. In other words, again only a simple connection between the bunched end of the traction elements and the collected end of the springs exists, which, again, are exposed to higher stress. If this fixing point tears off during operating the awning, there is no connection anymore between the traction elements and the springs, and the function of the articulated arm is compromised. European patent EP 0 489 186 A1 discloses a similar articulated arm comprising two parallel chains as traction elements which are individually connected to the two springs, respectively.
Therefore, it is an object of the present invention to provide an improved articulated arm that can longer resist the repeated alternating stress when the awning is reeled in and out without suffering damage.
According to one aspect of the invention, this object is achieved by an articulated arm for an awning, comprising a first arm part and at least a second arm part each having a longitudinal axis, an articulation having an articulation axis, the first arm part and the second arm part being connected to each other via the articulation, and the articulation axis running transversely to the longitudinal axes of the arm parts, at least two springs arranged adjacent to each other and each of the springs having a first end and a second end, the first ends being fixed at the first arm part, at least two traction elements each having a first end and a second end, the first ends being individually connected to the second ends of the springs, and the traction elements being led via the articulation to the second arm part and fixed thereto, wherein at least one traction element is assigned to each spring and wherein the traction elements are wire cables, which comprise, at least in their region which is led via the articulation, a plastic coat.
In this aspect, instead of fixing one single traction element with its end together onto the at least two springs, or instead of bunching several traction elements on one end and then, bunched, connecting with all springs together, it is provided, according to the invention, to assign to each existing spring at least one separate traction element, which is, then, fixed only onto the spring that is assigned to it. Each traction element, therefore, has to take up the force of only one spring, which reduces the stress of each individual traction element. Further, instead of using chains as traction elements, the traction elements are wire cables having a plastic coat at least in the region of the articulation. The plastic coat advantageously reduces friction and wear of the wire cables in the region of the articulation. Durability under load tests have shown that the endurance of the articulated arm according to the invention in comparison with known articulated arms is by far higher even than the endurance of articulated arms using chains.
Another advantage of this embodiment of the articulated arm of the invention is that, should one traction element tear, the at least one further traction element and the at least one further spring are still connected, so that the function of the articulated arm is at least partly maintained, and that then the connection still existing of the remaining traction element with the remaining spring is exposed to no higher stress than if all traction element spring connections were intact. This object of the invention is in that way completely achieved.
In another aspect, the traction element assigned to the corresponding spring is fixed, with its second end, individually on the second arm part. By this measure, the operational safety of the articulated arm is increased even further, as in this embodiment both ends of the traction element are fixed individually both to the assigned spring and to the fixation point on the second arm. Alternatively, however, if the traction elements are bundled, on their end fixed on the second arm part to one end, and the bundled end is fixed on the second arm part, the collection or bundling of the ends fixed onto the second arm part, which are still fixed individually on each spring, has the advantage that the traction elements can more easily be fixed when the articulated arm is mounted, since, then, only one end has to be fixed onto the second arm part.
In a further aspect, the springs are coil springs and an insert nut is fixed on at least one end of these springs, respectively, into which a suspension eyelet is screwed. This configuration of the springs also contributes to higher endurances of the articulated arm. In usual articulated arms, namely, coil springs are generally used, the ends of which are formed into a hook. Forming of a coil spring end into a hook leads, however, to material weakening and earlier material fatigue of the springs in the region of the hook-shaped formed ends.
By fixing an insert nut onto at least one end of the springs, as it is provided according to this aspect of the invention, into which a suspension eyelet is screwed, a fixation point for the traction element or for the fixation of the spring on the first arm part is created, which eliminates the need for the spring being formed and, thus, from experiencing material fatigue. It is then preferred if the insert nuts are rolled or pressed into the spring. By this measure, a particularly tight connection that can resist high stress is created between the insert nut and the spring.
In yet another aspect, at least two traction elements are assigned to each spring. In this embodiment, the at least two traction elements are preferably, according to the invention, individually fixed onto the spring assigned to them. By assigning at least two traction elements per spring, the endurance of the articulated arm can be increased even further.